Loongson Begins Posting Linux Patches For 3A6000 Series CPUs

While the Loongson 3A6000 processors have yet to be officially launched, rumors since last year put it on target for launching in the first half of this year and some claims that there is such performance uplift that these Chinese CPUs could rival AMD Zen 3 or Intel Tiger Lake levels of performance. Ahead of the 3A6000 series launch, Linux patches have begun appearing for these next-gen LoongArch processors.

The Loongson 3A5000 series is the current processors from this Chinese company and their first to be based on LoongArch, Loongson's in-house CPU ISA based in part on MIPS64 and inspiration from RISC-V. The Loongson 3A5000 series have been running on Linux well and Loongson engineers have upstreamed their LoongArch kernel patches as well as continuing to enable LoongArch support in more user-space software.

Today is the first time I've seen any Loongson 3A6000 series specific patches. A Loongson engineer posted this patch series adding a hardware page table walker. The patch notes that LoongArch 3A6000 series processors and newer have hardware page table walker (PTW) support that can handle all fast-paths of TLBI/TLBL/TLBS/TLBM exceptions by hardware. Software handling is only needed for the slow-paths, namely page faults.

Separately, another patch series today adds LoongArch DBAR with different hints. These hints for different memory barriers can bring performance improvements for the Loongson 3A6000 series.

With these two patch series out today from Loongson engineers and explicitly mentioning 3A6000 series support, presumably more Linux kernel enablement code will be on the way soon for these next-gen Chinese LoongArch CPUs being released this year.